This invention relates to a tracing paper product particularly intended for use by artists, architects and draftsmen whose work involves starting from source material contained on a sheet of paper and modifying the material by tracing parts of the source material onto an overlying sheet of tracing paper. Designers and Architects in particular make numerous versions of a basic plan or layout to determine the suitability of one or more of the versions to an assignment. Trial and error sketches are repeatedly made by tracing a basic design, such as the perimeter of a building plan, from another sheet and then filling out the plan with variations which the architect believes may accomplish the design objectives.
During this particularly repetitive exercise, it is common practice to use a particularly expendable type of tracing paper known in the field as "bumwad," "trash paper," "canary yellow" among others. The paper is relatively cheap, thin and is usually supplied in rolls from which a desired quantity is dispensed by the user. The tracing paper is then placed on a drafting table over a sheet of paper on which appears the source material to be traced. The underlying paper may be a blueprint, a sheet of other tracing paper or even a series of sheets of tracing paper. Tracing paper of this type is cheap, not intended for archival ues, is very translucent and thus a number of sheets can be superimposed on top of each other during the trial and error design process as desired.
The most common prior conventional attachment method involves simply taping the four corners of the tracing paper to the underlying sheet with drafting tape. This method requires several pieces of tape to be arbitrarily torn off from a roll to be applied at the four corners of the tracing paper. A reasonable amount of care must be taken in this process of smoothing the paper down before taping, in order to avoid wrinkles in the paper which tend to destroy the registration between the underlying graphic design and the traced design. Even if the tracing paper starts out relatively smooth, pencil lines and pressure applied by the hand of the artist can cause the paper to wrinkle or "travel."
Another, somewhat of an improvement, has been the invention of small paper dots having adhesive on one side which are more conveniently dispensed from a roll one-by-one and are used instead of having to tear off drafting tape to secure the corners of the tracing paper to the underlying sheet. While the dots are easier to dispense from the tape, they also do not necessarily keep the tracing paper from wrinkling or stretching.
It is possible, if one thinks or knows to do so, to manually spray the back of the tracing paper with an artist's adhesive after tearing of the tracing paper from the roll and before applying to the underlying sheet. However, this cannot be done manually consistently in a uniform manner. While the tracing paper can be made to cling to the underlying sheet, areas of light application will separate from the underlying sheet and cause a "bubble." Areas of heavy application can cause the tracing paper to adhere so firmly that it may well tear upon removal and can also leave a residue of adhesive which makes the underlying sheet unusable.